Also, @dhruv8sh has forked the Plasma 5 AlphaBlack Control widget and ported it to Plasma 6. It can be found at https://store.kde.org/p/2136860.

Porting to Plasma 6

After finally setting up a Virt-Manager VM with Plasma 6, I’ve been steadily porting my widget build scripts to Plasma 6.

Most of my old build scripts used kreadconfig5 to read data from the .ini like .desktop files to get the widget’s namespace (eg: com.github.zren.commandoutput) and ServiceType (eg: Plasma/Applet).

packageNamespace=`kreadconfig5 --file="$PWD/package/metadata.desktop" --group="Desktop Entry" --key="X-KDE-PluginInfo-Name"`
packageServiceType=`kreadconfig5 --file="$PWD/package/metadata.desktop" --group="Desktop Entry" --key="X-KDE-ServiceTypes"`

The ServiceType can be assumed if I only use this build script for widgets, but I still need to read the former in my ./install script since I need to check if the namespace is already installed to switch between kpackagetool6 --install and kpackagetool6 --upgrade since --install will fail if the widget already exists in ~/.local/share/plasma/plasmoids.

isAlreadyInstalled=false
kpackagetool5 --type="Plasma/Applet" --show="com.github.zren.commandoutput" &> /dev/null
if [ $? == 0 ]; then
	isAlreadyInstalled=true
fi
if $isAlreadyInstalled; then
	kpackagetool5 --type "Plasma/Applet" --upgrade ./package/
	restartPlasmashell=true
else
	kpackagetool5 --type "Plasma/Applet" --install ./package/
fi

Since Plasma 6 now forces the use of metadata.json, I now need a command that’ll read a JSON object key, using only the software installed by default on most distros. I need to check if jq is installed by default on every distro since that would simplify things. That said, every distro will have python3 installed so we can just use it’s json module.

packageNamespace=`python3 -c 'import sys, json; print(json.load(sys.stdin).get("KPlugin", {}).get("Id", ""))' < "$PWD/package/metadata.json"`

Where things become annoying is with parsing the ServiceType. By default, desktoptojson will convert X-KDE-ServiceTypes=Plasma/Applet in metadata.desktop to this in metadata.json.

{ "KPlugin": { "ServiceTypes": [ "Plasma/Applet" ] } }

However in Plasma 6, you manually need to convert it to:

{ "KPackageStructure": "Plasma/Applet" }

So we need to parse both cases in the build scripts.

packageServiceType=`python3 -c 'import sys, json; print(json.load(sys.stdin).get("KPackageStructure",""))' < "$PWD/package/metadata.json"`
if [ -z "$packageServiceType" ]; then # desktoptojson will set KPlugin.ServiceTypes[0] instead of KPackageStructure
	packageServiceType=`python3 -c 'import sys, json; print((json.load(sys.stdin).get("KPlugin", {}).get("ServiceTypes", [])+[""])[0])' < "$PWD/package/metadata.json"`
	echo "[warning] metadata.json needs KPackageStructure set in Plasma6"
fi

[Plasma 5] Parsing I18n in metadata.desktop

Next up was the problem I’d been dreading since metadata.desktop was deprecated in Plasma 5. Parsing/extracting i18n translations from the new metadata.json then modifying the JSON with the new translations.

With the old metadata.desktop, the xgettext and msgfmt tools had a built in ability to edit .desktop files.

# Note: xgettext v0.20.1 (Kubuntu 20.04) and below will attempt to translate Icon,
# so we need to specify Name, GenericName, Comment, and Keywords.
# https://github.com/Zren/plasma-applet-lib/issues/1
# https://savannah.gnu.org/support/?108887
find "${packageRoot}" -name '*.desktop' | sort > "${DIR}/infiles.list"
xgettext --files-from="${DIR}/infiles.list" --language=Desktop \
	-k -kName -kGenericName -kComment -kKeywords \
	-D "${packageRoot}"	-D "${DIR}"
	-o "template.pot.new" \
	|| \
	{ echoRed "[translate/merge] error while calling xgettext. aborting."; exit 1; }

touch "$DIR/LINGUAS" # List all available translation languages
for cat in `find . -name '*.po' | sort`; do
	catLocale=`basename ${cat%.*}` # "fr.po" => "fr"
	echo "${catLocale}" >> "$DIR/LINGUAS"
done

cp -f "$DIR/../metadata.desktop" "$DIR/template.desktop"
sed -i '/^Name\[/ d; /^GenericName\[/ d; /^Comment\[/ d; /^Keywords\[/ d' "$DIR/template.desktop"

msgfmt --desktop --template="$DIR/template.desktop" \
	-d "$DIR/" \
	-o "$DIR/new.desktop"

[Plasma 6] Parsing I18n in metadata.json

KDE might be using itstool I think (they use it in org.kde.plasmashell.metainfo.po) but plasma-desktop._json_.po which contains the metadata.json translations doesn’t reference it at all.

#. (itstool) path: component/name
#: org.kde.plasmashell.metainfo.xml:9
msgid "KDE Plasma Desktop"
msgstr "Bureau Plasma de KDE"

#: applets/activitypager/metadata.json
msgctxt "Name"
msgid "Activity Pager"
msgstr "Gestionnaire d'activités"

When I realized there wasn’t a simple tool to extract update metadata.json with translations, I realized I’d probably have to write something myself.

Extracting the Name and Description from metadata.json was fairly simple. Just read the keys from JSON and create a simple template.pot. We can just ignore filling out the .pot header as it gets overwritten in the xgettext --join-existing later on.

with open(self.jsonMetaFilepath, 'r') as fin:
	metadata = json.load(fin)
# This template header is overwritten later so the only changes needed is
# 'charset=CHARSET' => 'charset=UTF-8' so that xgettext doesn't complain.
# POT_DEFAULT_HEADER already has the charset=UTF-8 replaced.
newTemplateText = POT_DEFAULT_HEADER
kp = metadata.get('KPlugin', {})
trKeywords = [
	'Name',
	'Description',
]
relativeMetadataPath = os.path.relpath(self.jsonMetaFilepath, self.translateDir)
for keyword in trKeywords:
	keywordMessage = kp.get(keyword, '')
	keywordMessage = keywordMessage.replace('\"', r'\"')
	if keyword != "":
		# keywordText = f"#: {relativeMetadataPath}\nmsgctxt \"{keyword}\"\nmsgid \"{keywordMessage}\"\nmsgstr \"\"\n\n"
		keywordText = f"#: {relativeMetadataPath}\nmsgid \"{keywordMessage}\"\nmsgstr \"\"\n\n"
		newTemplateText += keywordText
with open(newTemplatePath, 'w') as fout:
	fout.write(newTemplateText)

Now the tricky part, parsing the translated language.po files, then editing the metadata.json.

Checkout the regex I used here: https://regex101.com/r/kEJCVL/5

github.com/Zren/plasma-applet-lib/…/kpac#L97

PoMessage = namedtuple('PoMessage', ['ctxt', 'id', 'str'])
class PoFile:
	def __init__(self, filepath):
		self.filepath = filepath
		self.text = None
		self.messages = []
		with open(self.filepath, 'r') as fin:
			self.text = fin.read()
		self.parse()
	@property
	def msgPattern(self):
		# Edit/Test: https://regex101.com/r/kEJCVL
		patt = r'(msgctxt[ \t]+(".*")[ \t]*\n)?'
		patt += r'((".*"[ \t]*\n)*)'
		patt += r'(msgid[ \t]+(".*")[ \t]*\n)'
		patt += r'((".*"[ \t]*\n)*)'
		patt += r'(msgstr[ \t]+(".*")[ \t]*\n)'
		patt += r'((".*"[ \t]*\n)*)'
		return patt
	def _joinMsgStr(self, line1, line234):
		if line1 is None:
			return None
		elif line234 is None:
			return line1.strip().strip('\"')
		else:
			lines = [line1] + line234.split('\n')
			msgstr = ""
			for line in lines:
				msgstr += line.strip().strip('\"')
			return msgstr
	def parse(self):
		for m in re.finditer(self.msgPattern, self.text):
			msgCtx = self._joinMsgStr(m.group(2), m.group(3))
			msgId = self._joinMsgStr(m.group(6), m.group(7))
			msgStr = self._joinMsgStr(m.group(10), m.group(11))
			msg = PoMessage(msgCtx, msgId, msgStr)
			self.messages.append(msg)
	def getMsgStr(self, msgid, msgctxt=None):
		for msg in self.messages:
			if msg.ctxt == msgctxt and msg.id == msgid:
				return msg.str
		return None

github.com/Zren/plasma-applet-lib/…/kpac#L881

with open(self.jsonMetaFilepath, 'r') as fin:
	metadata = json.load(fin)
trKeywordsMap = {
	'Name': '',
	'Description': '',
}
kp = metadata.get('KPlugin', {})
for keyword in trKeywordsMap.keys():
	trKeywordsMap[keyword] = kp.get(keyword, '')
for catFilepath in glob.glob(os.path.join(self.translateDir, '*.po')):
	catFilename = os.path.basename(catFilepath)
	catLocale = os.path.splitext(catFilename)[0]
	catFile = PoFile(catFilepath)
	for keyword, msgid in trKeywordsMap.items():
		catMsgStr = catFile.getMsgStr(msgid)
		catKeyword = f"{keyword}[{catLocale}]"
		if kp.get(catKeyword) != catMsgStr and catMsgStr != "":
			kp[catKeyword] = catMsgStr
with open(filepath, 'w') as fout:
	json.dump(data, fout, ensure_ascii=False, indent='\t', sort_keys=True)
	fout.write('\n') # Trailing newline at EOF

An important part was to use ensure_ascii=False in json.dump() to keep the unicode text.

Drawing the rest of the Owl in Plasma 6

Okay now I needed to do everything else listed on:
https://develop.kde.org/docs/plasma/widget/porting_kf6/

Well since I have like a dozen widgets, I needed to automate some of this.

Manipulating metadata.json with python3 is easy enough as we demonstrated above.

github.com/Zren/plasma-applet-lib/…/kpac#L1055

For the rest, the easiest way would be with some simple sed text replacements. To make life easier I just kept using python though.

github.com/Zren/plasma-applet-lib/…/kpac#L1216

Then I grepped for the new KSvg. namespaces, and added an import org.kde.ksvg as KSvg at the top of the file if it was missing. I may or may not have forgotten to write the rest of the file contents and deleted a few files when testing. Glory to git checkout path/to/file.txt for saving my bacon here.

Lastly I detected if the file was main.qml, and replaced any line starting with ^Item\s*\{ with PlasmoidItem { since I usually keep my code properly indented.

As always, creating a list of all the various Plasmoid.___ properties to replace was a pain.

[Plasma5] Global plasmoid property (which is also attached to the widget root item as Plasmoid)

[Plasma6] PlasmoidItem root item

[Plasma6] Attached Plasmoid similar to Layout which dynamically grabs the value from the Applet class

Since Plasma6 made things a little confusing as to what is in PlasmoidItem {} and what is accessed with Plasmoid.___ I settled on the following for now:

github.com/Zren/plasma-applet-lib/…/kpac#L1185

plasmoidPropsPorted = [
	# AppletQuickItem
	'switchWidth', 'switchHeight',
	'compactRepresentation', 'fullRepresentation',
	'preloadFullRepresentation', 'preferredRepresentation',
	'expanded', 'activationTogglesExpanded',
	'hideOnWindowDeactivate',
	# PlasmoidItem
	'toolTipMainText', 'toolTipSubText', 'toolTipTextFormat', 'toolTipItem',
	'hideOnWindowDeactivate',
]
for prop in plasmoidPropsPorted:
	line = line.replace(f"Plasmoid.{prop}:", f"{prop}:")

The last things I had to do manually was convert the plasmoid.setAction('refresh, ...) calls to the new Plasmoid.contextualActions: [ PlasmaCore.Action {...} ] which would be a tad too complicated to automate.

I was able to quickly sed replace my plasmoid.action('configure').trigger() trick to open the config dialog automatically when testing though which I have in most of my widgets.

PlasmoidItem {
	Component.onCompleted: Plasmoid.internalAction("configure").trigger()
}

In Closing

Overall, with my new script it should be as easy to do most of the dull text replacement work.

The hard part will be converting any deprecated QQC1.Buttons and other GUI elements that might have custom styling to their QQC2.Button counterparts. TiledMenu and EventCalendar will probably be more annoying to port than just running the following:

github.com/Zren/plasma-applet-lib/…/kpac

python3 ./kpac updatelib ../plasma-applet-lib
python3 ./kpac plasma6
# Scan changes 
python3 ./kpac i18n # Update metadata.json and convert .po => .mo
git commit . -m 'Update'
python3 ./kpac build # Create a zipped .plasmoid

I got too tired last night, so firsts things up is porting SimpleWeather today since it’s basically the same code as the other weather widgets.

This “widgets have been updated” blog post rambled on more than I expected, sorry bout that.